I'm assuming you mean USS vs. OSS, right? Are you trying to decide what might work better for you? I've only ridden OSS, so it would be hard for me to compare. But you should test ride to see what you like better.

__________________
"The difference between genius and stupidity is that genius has its limits."
-- Albert Einstein

My Vision R-42 is convertible, and I've used it in both configurations. I find that I prefer OSS for a couple of reasons. First, even though I rode the bike in the USS configuration for over a year after I bought it, I still felt more in control with OSS. At least on the Vision, the USS bars can hit the seat during extreme manuvers. It never happened very often, but just knowing that it could happen made me a little uncomfortable. Second, I like the OSS bars because I can hang stuff (computer, lights) on them. Finally, I think I felt a little too "exposed" with USS. I prefer hiding behind something, even if it's only a set of handlebars.

The bottom line is that, like so many other things, it's a matter of personal preference. Try both for an extended period of time if you can, then make your choice.

- Very confortable, especially on long distances
- Affords a much better view of the landscape ahead
- Leaves the top of the bike uncluttered (easier to climb on)
- Great to pull on the handlebar when climbing with direct USS
- You feel like you're piloting a jetplane

USS cons:

- Limited turning radius (even more so with direct USS)
- If cowhorn handlebar, brake/shift levers mounted in reverse, or brake levers in reverse and barcons for shifters
- Indirect USS (with a linkage) can be fragile if the bike falls over and damages the steering pin
- Some people don't like to ride with their bellies "exposed" (psychological issue? I've heard this several times from people who tried my bike)

OSS pros:

- More intuitive, less learning curve
- Several positions available depending on the geometry of the bike: "superman" position or "praying hamster" position
- More aerodynamic
- Shifters and brakes mounted normally
- Allows you to mount accessories on the handlebar
- Better turning radius

OSS cons:

- Tiring over time
- Pretty huge tiller effect on some bike that can limit the effective turning radius
- harder to get onto the bike because the stem is in the way
- You'll mash your nuts against the stem in case of frontal collision, instead of being simply ejected.
- Stem can be flexy when pulling on the handlebar.

My first recumbent was an infinity with USS, I had a circulation problem from my arms hanging down on longer rides; same things happens when I go for long hikes. My hands and fingers swell up and produce a slight pressure problem. Since '92 I have built all my bikes with OSS which I find quite comfortable, you just have to get the ergonomics correct.

I got an Actionbent Jetstream II USS. My first bent, so I can't compare with other bents, but I love this bike. It's a whole new experience for me.

I assembled it myself, with the exception of the derailleur hanger. I couldn't get the threads started, so my LBS man did that for me. It took me all day, with watching tv and relaxing, but it was pretty simple.
She's a pretty bike, but she's got more than just good looks.

It rides well, is comfortable, and is stable (except that I weave a bit, but that's not the bike's fault. ) It takes the bumps well. I'm still slow on it, because I don't have the leg strength yet--seems like I've lost years off my legs, if you know what I mean. Instead of taking me an hour to go 14 miles to work, it took 70 minutes! Still, I made the switch to recumbent for commuting, and I'm not going back (as far as I can tell.)

I got an Actionbent Jetstream II USS. My first bent, so I can't compare with other bents, but I love this bike. It's a whole new experience for me.

It rides well, is comfortable, and is stable (except that I weave a bit, but that's not the bike's fault. ) It takes the bumps well. I'm still slow on it, because I don't have the leg strength yet--seems like I've lost years off my legs, if you know what I mean. Instead of taking me an hour to go 14 miles to work, it took 70 minutes! Still, I made the switch to recumbent for commuting, and I'm not going back (as far as I can tell.)

Congrats on your new ride! I found too that I was slower at first, on my bent. But in time you'll probably be just as fast and much more comfortable to boot. I could never give up the comfort I find on my bent.

__________________
"The difference between genius and stupidity is that genius has its limits."
-- Albert Einstein

In January of 2001, I bought a third-hand used Linear long wheelbase recumbent bike. It had the ape-hanger style above seat steering already installed on the bike. The original owner had converted from USS and saved the parts parts that the bike shop had taken off it. As a lark, I installed the USS components while keeping the brake and shift mechanisms on the old bars and rode it with both in place. I found having my hands hang down resting on the USS handlebars to be more comfortable than having my hands up in the air. After about a month I moved the brake levers and shift levers to the USS and removed the other bars. I also own an Haluzak Horizon SWB and two trikes, all with USS. Others will disagree but I would not have it any other way now that I have ridden recumbents for 5 years. Try both and see which one you like.